A screenshot of Baldur's Gate
, showcasing the user interface designed by BioWare
in order to provide relative ease in playing the game, with the UI template used in other Forgotten Realms-licensed games, such as Icewind Dale
. The game also relies heavily on plot and dialogue as driving factors behind how it conveys the main story.
Players conduct the game from a top-down isometric third-person perspective, creating a character for each playthrough who then travels across pre-rendered locations, taking on quests, recruiting companions to aid them, and combating enemies, while working towards completing the game's main story. Control is done through a user interface that allows a player to move characters and give them actions to undertake, review information on on-going quests and the statistics of characters in their party, manage their inventories, organize the formation of the party, though the screen does not need to be centered on the characters being controlled and can be moved around with the mouse and keyboard, the latter also capable of accessing various player options through keyboard shortcuts. All of the gameplay mechanics were coded to conform to the Advanced Dungeons & Dragons 2nd edition role-playing rules, with game automatically computing the rule intricacies, including tracking statistics and dice rolling. Although the game is conducted in real-time, some elements of the ruleset used in the coding were modified to allow it to feature a pausable real-time mode, allowing players to pause the game at any time and prepare what actions a character do, including the ability to set the game to automatically pause at preset points in combat. A new playthrough requires the player to either create a new player character (PC), or import one they exported from a previous playthrough. Every new character requires the player to determine what their name, gender, race, class, and alignment are, and what ability scores and weapon proficiencies they have, with thieves requiring points be allocated between their thieving skills, and spellcasters having a few spells set up for them - those using priest spells have them available for use from the start, while those using wizard spells add them to their spellbook and have one primed for use at the start of a new game. New PCs can be multi-class, but must adhere to the restrictions that come from this, in accordance to the 2nd edition rules; a character who is both a cleric and a fighter, may only use weapons of the former class.
The game's main story is divided up into eight parts - a prologue and seven chapters - with each requiring the player to complete a specific task in order to complete it; while free exploration of the game's world map is allowed from the outset upon completing the prologue, some areas are not accessible until the player has advanced to a specific chapter. With the exception of imported characters, all PCs begin off as weak characters from the start, but eventually grow stronger as the player explores the game's world, completing both the major quests and the game's large variety of side quests, killing hostile enemies, earning experience points to level up their character, finding new spells to use and new pieces of equipment to wear, and recruiting a variety of companions, each with different classes and skills, to aid them in their travels. A PC may have up to five companions travelling with them in their party, with the player free to decide who to recruit and who to dismiss from the party. Upon reaching the experience threshold for their current level, defined by their class, both the PC and companions can level up, increasing their hits and occasionally improving their weapon proficiencies, with thieves provided additional points to distribute between their skills, and spellcasters gaining access to additional spell slots, sometimes gaining access to new ones for higher levels of magic. All characters are limited to a maximum number of 89,000 experience points in the game, with characters who multi-class being also affected by this cap - an elf who uses two classes may only earn half the cap in each, with experience divided equally between the two classes, while a human who dual-classed after earning a third of the cap in their base class, may only earn the other two thirds in their second class.
The main user interface consists of three action bars surrounding the main screen. The first bar consisting of buttons to the various options players can use, including a map of the party's location and the world, the journal that logs all details of notable events and all on-going and completed quests, character records for each member of the party, the inventories for each character, spellbooks containing all spells available for spellcasters, a time display that also acts as the pause mechanism when clicked, and the various game options. The second bar consists of the portraits of each character currently in the party, detailing their hit points, their order, and any positive and negative effects they are experiencing, with the portrait switching from colour to greyscale when the character has died. The third bar provides specific actions depending on the number of characters being controlled by the player; if one is selected, the player has the ability to switch between the weapons they are using, use any spells and items set up for quick use, and utilises a character's special abilities or those of certain pieces of equipment, but if more than one is selected, the bar displays options for conversing with or attacking NPCs, regardless of being friendly, neutral or hostile, stop what is being done, and change their formation to those available in the game.
The inventory system used in Baldur's Gate follows the conventions of the "paper doll" mechanics, in that each character can equip items depending on what type they are - weapons, ammo, armour, helmet, necklace, rings, belt, cloak, feet, and usable. The number of items a character can both equip and carry is affected by their weight limit, which is determined by their Strength ability score; going over this limit will encumber the character causing them to move slowly or prevent them moving altogether, until they remove items from their inventory. The system notably indicates what equipment a character can not use as defined by their class, which also determine how many weapon slots they have available for weapons; by default, all character have two weapon slots along with an off-hand slot for shields and weapons, but some classes allow character to one or two extra weapon slots to use. In addition, characters may equip three stacks of ammo for ranged weapons (bows, crossbows and slings), and use three different types of usable items (potions, scrolls and wands). Items can be examined in the inventory, though most enchanted items require identification before their properties are known, while any cursed equipment can't be removed unless through magic or visiting a temple. Any potions found can be used without being set up for quick use, while mages can learn spells from scrolls that they do not have knowledge of and have room for in their spellbook; unlike priest classes, who have access to all the spells of each level magic upon acquiring a slot in that level, mages need to learn spells from scrolls found in their travels or bought from shops, but can learn those of higher levels that they do not have spell slots for, though higher game difficulties incur the possibility of failing to learn a new spell. In addition, any spells set to a spell slot cannot be used until the spellcaster rests first to "memorise" it.
Dialogue is an important aspect of the game, which relies heavily on it. Conversation can be initiated by players selecting a member of the party and clicking on a friendly or neutral NPC, though some conversation are initiated automatically when characters come close to them, and while most conversations are mainly text-based, some include spoken dialogue. Most conversation include a list of responses that a character can use, some that can provide information on certain topics, lead to quests, or access services, while others can influence a situation, such as provoking a fight, or finding another way to solve a problem. Certain NPCs offer services that character can use when talking with them, including shops where characters can buy and sell items and get unknown enchanted items identified, inns where the party can rest in safety and recover lost hit points and memorise spells, and temples where characters can pay for healing services, such as resurrecting a dead party member.
Other features that affect gameplay include:
- The ability to customise their PC after creation, albeit with some restrictions.
- The ability to change the primary and minor colours used by each character.
- The ability to switch on/off the game's AI, and change what AI script a character uses ; one script might dictate they proceed to engage an enemy when spotted, while another might dictate they keep their eye out for traps.
- Most locations are hidden when first visited but are revealed as the character moves around them. A fog of war effect hides explored areas when the player's characters move away from them.
- A reputation system that tracks the moral actions of the PC and affects how they are perceived, changing if they resolve a problem or commit a crime in the view of witnesses. Higher reputations cause shops to decrease prices, while lower reputations cause shops to increase prices. Lower reputations may also lead to the character being attacked when in town. Companions are also affected by reputation, with evil companions leaving the party, even attacking it, if it is high, and good and neutral companions leaving when it is low. Some side quests also require a minimum reputation to begin. Certain NPCs may also react negatively or positively depending on their alignment and the player's reputation.
- The ability to keep track of in-game time through the changes in lighting and the activity that is occurring. Characters become fatigued after spending a full in-game day, especially after travelling long distances between world map locations, and must rest to recover, either in an inn or camping out in the countryside/within a dungeon.
- Characters can be ambushed when camping out or travel long distances between world map locations.
- Players can play either in single-player mode, or in multiplayer mode. The latter allows up to six players to work together online with their own created characters.